Clinical trials using single agent tumor necrosis factor have been ongoing for approximately the past 2 years. Minimal antitumor efficacy of this drug has been observed to date. In vitro studies with TNF, however, have demonstrated that the combination of gamma interferon with tumor necrosis factor results in significant augmentation of antitumor effects. These results have been confirmed in vivo in animal models. However, substantial enhancement of TNF-related toxicity has also been observed using this drug in combination with gamma interferon. In this study, we intend to investigate the immunomodulatory and toxic effects of the combination of TNF and gamma interferon. To date, 9 patients have been admitted in this study at the lowest 3 dose levels. No antitumor effects have been observed. The results of immunologic evaluations of these patients is still in progress. Toxicity observed so far has included fever, chills, modest hypotension, nausea and vomiting, fatigue, and muscle soreness at the site of injection of the tumor necrosis factor but not at the site of injection the gamma interferon.